Film projection apparatus



Feb. 4, 1947. A. A. GRADISAR EI'AL FILM PROJECTION APPARATUS 3Sheets-Sheet 1 Filed Dec. 8, 1945 INVEN TOR.

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FILM PROJECTION APPARATUS Filed Dec. 8, 1945 L a Sheets-Sheet 2 J I 7/,x 5? I III a I 5 so g? 24: i R 27 2 A l 35 H l :3 r l I l 1 I l J 4 I lI ri" INVENTOR.

am A. GRADISM! 9 y GEORGE E SCHENK Y W 0W ATTORNEY Feb. 4, 1947.

A. A. GRADISAR Er AL 2,415,281 FILM PROJECTION APPARATUS 3 Sheets-Sheet-3 Filed Dec. 8, 1945 INVENTOR.

ALBIN KGRADISAR GEORGE F. SCHENK ATTORNEY Patented Feb. 4, 1947 OFFICEFILM PROJECTION APPARATUS Albin A. Gradisar and George F. Schenk,Buffalo, N. Y., assignors to American Optical Company, Southbridge,Mass., a voluntary association of Massachusetts Application December 8,1945, Serial No. 633,586

(CL era-24) 3 Claims.

This invention relates to projecting apparatus in which the materialbeing projected onto a screen or the like may be shifted with greataccuracy so as to move the projected image to a predetermined or desiredposition.

More particularly, the present invention is applicable to the gate of aprojecting apparatus having an optical projection system which isadjustable to vary the size of image produced without varying the imageplane of the system. Be-

cause with such variation in the size of image,

a shifting of the gate through a unit distance will cause a particulardetail of the image to be shifted more at large magnification than atsmall magnification, it has been necessary to devise a control for theshifting of the gate which will operate at more than one speed.

Accordingly, an object of the invention is to provide a counterconnected to an actuating member of a slide for shifting the gatelaterally, the connection to the counter including change speed gearingso that the counter records the adjustment of the slide at two difierentrates.

The invention is applicable to various projecting apparatus in which theoptical projection systern is adjustable to vary the size of image Dro-A duced or where various magnifications of objects are projected on thescreen. In order to clearly illustrate one embodiment of the invention,we have shown the control mechanism connected to projecting apparatus ofthe type disclosed and claimed. in copending application for Projectionapparatus, W. F. Peck et al., Serial No. 535,306, filed May 12, 1944.

In the accompanying drawings which illustrate the invention as appliedto projection apparatus of the above identified type:

Fig. 1 is a view in front elevation of projection apparatus providedwith the control mechanism embodying the invention;

Fig. 2 is a central sectional view taken on the line 2-2 of Fig. 1looking in the direction of the arrows;

Fig. 3 is an enlarged view partly in section of the counter shown inFig. 2 and driving con-- nections therefor, the section being takensubstantially on the line 33 of Fig. 4;

Fig. 4 is an end elevation looking from the left of Fig. 3, the controlknob being omitted; and Fig. 5 is a detailed sectional view, the sectionbeing taken on the axis of the control knob.

The projecting apparatus which has been selected for illustration isself-contained in that the light source with the cooperating condensinglenses, the objective and occular, the reflectors and a translucentscreen for receiving the projected image are grouped compactly togetherand carried by a mount 1 (see Fig. 2). The mount 7 extends from acylindrical housing 8 which has aligned openings 9 and I0.

A partial reflector l2 within the cylindrical housing 8 is inclined atsuch an angle (approximately 45) as to permit the observer to lookthrough the aligned openings 9 and I0 and match the image appearing onthe translucent screen l3 of the projecting apparatus with a chart orthe like which can be seen through the opening l0.

Referring to the projecting apparatus which is best seen in Fig. 2 thelight source is a lamp l5 with which the condensing lenses l6 cooperatefor passing a concentrated beam of light through the material, generallya film or plate, which is to be projected and which is held between thepressure plates ll of the film gate indicated in general by the numeral18. By means of the handle l9 the pressure plates may be separatedduring movement of the film from reel 20 to reel 20A to preventscratching or marring of the surface thereof.

The light transmitted through the material in the gate i8 is returned ina direction substantially parallel to the axis of the condensing lensesI6 by a double reflecting prism 2| having a reflecting face 2|A-inalignment with the film gate and a second reflecting face MB inalignment with the projection objective.

With this objective 23 cooperates an ocular 24. In order that the imageproduced by the ocular 24 may be projected upon the screen la, areflector 28 is aligned with the ocular and a second reflector 21cooperates therewith to direct the light rays to the screen I3.

In this projection apparatus the object plane (determined by thepressure plates l1) and the image plane (determined by the translucentscreen l3) do not vary; but the extent to which the image is magnifiedis varied by changing the optical spacing of the objective 23 and theocular 24. For proper illumination at all times, the

lamp l5 together with the condensing lenses 16 H which is adjusted.longitudinally of the optical axis upon rotation of the control knob 3|.

This same control knob 3| controls the size of the projected image onthe screen I! in that rotation of the control knob 3i causesdifferential movement of the objective 23 and ocular 24.

As a further refinement, the objective 23 is adjustably mounted on thegib 33 so that the image may be more clearly focused on the screen Foradjustment of the ocular 24 there is provided a screw 35 driven by mitergears 38 and 31. The screw 35 adjusts the position or the card whichbrings about differential movement of theocular 24 with respect to theobjective 23. The

miter gears are actuated by the knob 39 (see Fig 1).

In order to vary the magnification or image observed 'on the screen It,the control knob 31 is rotated. This control knob is connected not onlyto the ocular 24 and'objective 23 but also to the slide 30 carrying thelamp I5 and condensing lenses l6 and the movement of the slide 30 is socalculated as to image the filament of the lamp l5 approximately at thefirst focal point of the objective 23 as the latter is moved toward andaway from the object plane along the optical axis of theprojectingsystem. As the control knob ii is rotated the ocular does notmove at the same rate as the objective, but the ocular moves in the samedirection as the objective only until the mid-point of the excursion ofthe objective is reached at which time the ocular 24 reverses itsdirection of movement and moves in the opposite direction untilitreaches its original position. At this point the limit of variaton ofmagnfication has been reached.

The film gate l8 and the control mechanismtherefor, to which the presentinvention more particularly pertains, includes the pressure plate H. Thefilm gate itself I8 is mounted on cross slides 4| and 42 at right anglesto each other. The cross slide 4| is actuated by a screw 43 and thecross slide 42 is actuated by a screw 44 In addition, the film gate maybe rotated by means of a turntable 45, rotation of the turntable. beingaffected by a tangent screw 48 (see Fig. 1).

When a screw 43 or 44 is rotated to shift its respective slide 4| or 42transversely relative to the optical path of the projecting lens system,the image is correspondingly shifted on the screen I3. In order toaccurately control such lateral shifting or in order to accuratelymeasure the extent to which the image has been shifted, a counter isoperatively connected to each of the two screws 48 and 44. Since bothmechanisms are practically identical only the control mechanism forthe'screw 44 will be described.

.The shaft I50 of the screw extends through a bracket plate 49.

The screw 44 has been described as a unitary element; but forconvenience in assembling and manufacture the same may comprise inaddition to the shaft 60 anextension shaft 5i carrying the knob 52. Tothe extension 5| is secured by means of a set screw 53 a sleeve 54carrying a gear I55. This gear is of course driven by the screw 44.

sleeve 54 to swing about the axis of the gear 55. I

This support or shift lever 51 mounts two gear couples, one gear of eachgear couple being continuously in mesh with the gear 55. As is clearlyapparent from Fig. 4, upon swinging the support or shift lever 81 in onedirection the other gear "is-swung in the opposite direction the othergear of the lower speed gear couple is caused to mesh with the idlergear 80. This idler gear 80 is mounted on a stud 81 (see Fig. 3) andmeshes with a pinion 82 on the drive shaft 83 of the counter 84. Thecounter 84 may be of the usual commercial form such as a high-speedcounter known as Modified Veeder-Root catalog #640-28 and provided withthe reset knob 85. This counter 84 is mounted on an extension 88 of theplate bracket 49.

The low speed gear couple comprises a pair of gears 88 and 88 mounted ona stud 10 carried by the support 51 and the high speed gear couplecomprises gears 12 and 13 mounted on a stud I4 carried by the support51.

A spring actuated click 15 1s arranged to drop into a notch 16 in thesupport 51 in neutral position of this support or shift lever 51. Thisholds both gear couples out of mesh with the idler gear 60.

When the observer, looking through the aligned openings 8 and i0,desires to accurately match the projected image with a chart or the likeupon which the image is superposed due to the partial reflector l2,either the screw 43 or the screw 44 is rotated until desired placing orcoincidence is obtained. The accurate amount of the angle of rotation ofthe screw is recorded by the counter 84. Because of the difference inmagnification brought about by, the differential 35 movement of theobjective 23 and ocular 24, or by varying the magnifications of thefilm, it is necessary to rotate the counter 44 at different speeds. Thisis accomplished as above explained by the swinging of the support orshift lever 51 so that either the high speed or the low speed gearcouple, is brought into mesh with the idler gear 60. As a result, theaccurate control of the position of the gate i8 is made possible eventhough the projecting apparatus has variable magnifications.

While we have illustrated and described a preferred embodiment which'ourinvention may assume, it will be understood that our invention may beotherwise embodied and practiced within the scope of the followingclaims.

We claim:

1. In projecting apparatus having an optical projection systemadjustable .to vary the size of image produced without varying the imageplane of said system, the combination of a gate for positioning thematerial to be projected in the object plane of said system, a slide forshifting said gate laterally in said object plane relative to theoptical path of said system, a rotatable actuating-member for saidslide, a counter for indicating the angle through which said actuatingmember is rotated, and change speed gearing operatively connecting saidcounter to be driven by said actuating member at either of two speedsselectively including a gear driven by said actuating member; a supportpivotally mounted on the axis of said gear, a high speed gear coupleanda low speed gear couple bothcarried by said support and both meshingwith said first men- 2. In projecting apparatus having an opticalprojection system adjustable to vary' the size of image produced withoutvarying the image plan of said system, the combination according toclaim 1 including a spring actuated click for maintaining saidgear'support in neutral position, neither gear couple being in meshwhile said support is in said position.

3. In projecting apparatus having an objective and an ocular and meansfor changing the optical spacing therebetween to vary th size of imageproduced without varying the object and image planes of said system, thecombination of a gate for positioning a film tobe projected in theobject plane of said objective, a slide for shifting said gate laterallyin said object plane relative to the optical path of said lens system,

a screw for actuating said slide, a counter for indicating the anglethrough which said screw is rotated, and change speed gearingoperatively connecting said counter to be driven by said screw at eitherof two speeds selectively including a gear driven by said screw, a shiftlever pivotaliy mounted on the axis of said gear, a high speed gearcouple and a low speed gear couple both carried by said lever and bothmeshing with said first mentioned gear, and a counter driving gearpositioned to mesh with and be driven by one of said gear couples whensaid lever is swung in one direction and to mesh with and be driven bythe other gear couple when said lever is swung in the other direction.

. ALBIN A. GRADISAR. GEORGE F. SCHENK.

